Control system of an internal combustion engine

ABSTRACT

Control and regulation system of a combustion unit ( 10 ) of the type comprising a combustion chamber ( 11 ) and a catalyst ( 40 ), the control and regulation system comprising: - an acquisition device of signals proportional to functioning parameters characteristic of the functioning state of the combustion unit ( 10 ), an electronic data processing unit ( 30 ) connected to the signal acquisition device from which it receives signals, a control and regulation program associated with said electronic data processing unit ( 30 ), a first fuel distribution valve ( 20 ), a second air distribution valve ( 21 ), a data base associated with said electronic data processing unit ( 30 ), the electronic data processing unit ( 30 ) receives signals from the signal acquisition device, processes them and regulates the opening of the first valve ( 20 ) and second valve ( 21 ) to minimize the polluting emissions of CO and Nox of the combustion unit ( 10 ).

The present invention relates to a control and regulation system of acombustion unit equipped with a catalyst, in particular for controllingand regulating the functioning of the catalyst in order to reducepolluting emissions and increase the life of the catalyst.

A combustion unit normally comprises a first combustion chamber, acatalyst and a second combustion chamber.

The combustion chamber also includes an inlet duct for fuel, a secondinlet duct for the compressed air coming from a compressor and a thirdoutlet duct of the exhaust fumes.

The catalyst functions correctly and therefore allows lows the abatementof polluting emissions such as CO and NOx, when its functioningtemperature is within a pre-established temperature range, typical forits correct functioning.

For operating temperatures that do not fall within this temperaturerange, on the other hand, the catalyst does not function correctly anddoes not adequately reduce the CO and NOx polluting emissions.

One of the disadvantages is that with current catalyst combustion units,the abatement of polluting substances is not guaranteed, as the catalystmay have a functioning temperature that does not fall within the typicaltemperature range for its correct functioning.

Another drawback is that with present catalyst combustion units, if saidcatalyst functions at temperatures lower than those of the typicaltemperature range, it could become polluted, necessitating its earlysubstitution.

Another disadvantage is that with the catalyst combustion unitscurrently used, if these function at temperatures higher than thoseincluded within the range typical for the correct functioning of thecatalyst, said catalyst deteriorates and ages more rapidly, thus havinga shorter useful life.

Yet another drawback is that it is not possible to have a correctfunctioning temperature of the catalyst with variations in theenvironmental conditions, such as, for example, the temperature,pressure and humidity of the air.

An objective of the present invention is to provide a control andregulation system of a combustion unit capable of minimizing pollutingemissions also with variations in the environmental conditions, such asthe temperature, pressure and humidity of the air.

A further objective is to provide a control and regulation system of acombustion unit wherein the functioning temperature of the catalyst isalways within the typical range for its correct functioning.

These objectives according to the present invention are achieved bymeans of a control and regulation system of a combustion unit which,through the detection and processing of characteristic functioningparameters of the combustion unit itself, regulates it so as to reduceCO and NOx polluting emissions to the minimum.

An aspect of the present invention relates to a control and regulationsystem of a combustion unit (10) of the type comprising a combustionchamber (11) and a catalyst (40), said control and regulation systemcomprising:

-   -   an acquisition device of signals proportional to functioning        parameters characteristic of the functioning state of the        combustion unit (10),    -   an electronic data processing unit (30) connected to the signal        acquisition device from which it receives signals,    -   a control and regulation program associated with said electronic        data processing unit (30),    -   a first fuel distribution valve (20),    -   a second combustion air regulation valve (21),    -   a data base associated with said electronic data processing unit        (30),    -   said electronic data processing unit (30) receives signals from        the signal acquisition device, processes them and regulates the        opening of the first valve (20) and second valve (21) to        minimize the polluting emissions of CO and NOx of the combustion        unit (10).

The characteristics and advantages of a control and regulation system ofa combustion unit according to the present invention will appear moreevident from the following illustrative and non-limiting description,referring to the enclosed schematic drawings in which:

FIG. 1 is a schematic view of a control and regulation system of acombustion apparatus according to the present invention.

With reference to the figure, this illustrates a preferred embodiment ofa control and regulation system of a combustion unit 10.

The control and regulation system comprises a signal acquisition devicecapable of detecting at least one signal which is characteristic of thefunctioning of the combustion unit 10.

The control and regulation system preferably comprises a first fueldistribution valve 20 and a second air-flow regulation valve 21.

The control and regulation system comprises an electronic unit 30 and asignal acquisition device capable of detecting signals proportional tocharacteristic functioning parameters of the combustion unit 10.

The electronic unit 30 is connected to the signal acquisition device.

Furthermore, said electronic unit 30 is connected and controls the firstvalve 20 and the second valve 21.

The control and regulation system also comprises a program associatedwith said electronic data processing unit 30.

The control and regulation system preferably comprises a data baseassociated with said electronic data processing unit 30.

Said electronic unit 30 controls the parameters characteristic of thefunctioning state of the combustion unit 10 and, on the basis of these,regulates the opening of the first valve 20 and the second valve 21.

Said combustion unit 10 includes a combustion chamber 11 in turncomprising a first area 12, a second central area 13 where the catalyst40 is positioned, and a third area 14.

Said combustion unit 10 preferably comprises a first inlet duct 71 forthe fuel, a second inlet duct 72 for the compressed air, an outlet duct73 for the exhaust gases.

Said combustion unit 10 comprises a third inlet duct 74 for the fuel.

Said combustion unit 10 also comprises a duct 75 which connects a firstarea 12 and a third area 14 of the combustion chamber 11.

The second valve 21, which regulates the air that flows through it, ispositioned on the duct 75.

Said combustion unit 10 is connected to a compressor 50 and a turbine80.

Said compressor 50 compresses the air, which is then introduced into thesecond inlet duct 72.

Said turbine 80 receives hot air from the outlet duct 73.

The second inlet duct 72 is connected to the first area 12 of thecombustion chamber 11, so that the compressed air coming from thecompressor 50 flows into the combustion chamber 11.

The first inlet duct 71 is connected to the combustion chamber to allowthe fuel to enter the first area 12, whereas the third inlet duct 74 isconnected to the combustion chamber to allow the fuel to enter betweenthe first area 12 and the second area 13.

The first valve 20 receives the fuel from a main duct 70 and distributesit between the first inlet duct 71 and the third inlet duct 74.

The signal acquisition device comprises a series of sensors suitable fordetecting signals proportional to parameters characteristic of thefunctioning state of the combustion unit 10.

This series of sensors comprises a number of temperature sensorssituated in the combustion chamber 11.

Said series of temperature sensors comprises a first set of temperaturesensors 60, a second set of temperature sensors 61 and a third set oftemperature sensors 62.

Said series of sensors also comprises pressure sensors 63 for measuringthe pressure of the compressed air coming from the compressor 50,temperature sensors 64 for measuring the temperature of the compressedair leaving the compressor 50, pressure sensors 65 and temperaturesensors 66 of the exhaust gases at the outlet 76 of the turbine 80.

The pressure and temperature of the exhaust gases at the outlet of theturbine 80 are detected by means of the pressure sensors 65 andtemperature sensors 66, respectively.

The first series of temperature sensors 60 and the second series oftemperature sensors 61 are situated close to the catalyst 40.

In particular, the first series of temperature sensors 60 is positionedbetween the first area 12 and the second area 13 of the combustionchamber 11, whereas the second series of temperature sensors 61 issituated between the second area 13 and third area 14 of the combustionchamber 11.

Most of the compressed air coming from the compressor 50 enters thefirst area 12 of the combustion chamber 11 through the second inlet duct72 and is mixed with the fuel introduced into the first inlet duct 71,the remaining part of compressed air passes through the duct 75,re-enters downstream of the area 14 of the combustion chamber 11 anddoes not take part in the combustion process.

The combustion reaction then takes place, of the fuel with thecompressed air, with the consequent heating of the air and fuel mixture.This allows the functioning temperature of the catalyst to be raised.

Fuel coming from the third fuel inlet duct 74 is then added to themixture thus heated.

The combustion reaction mainly takes place in the second area 13 of thecombustion chamber 11 and is completed in the third area 14.

The first series of temperature sensors 60 detects the inlet temperatureof the catalyst 40, the second series of temperature sensors 61 detectsthe intermediate temperature of the catalyst 40, the third series oftemperature sensors 62 detects the outlet temperature of the catalyst40.

The ideal outlet temperature values which should be reached to enable,under certain environmental conditions, the correct functioning of thecatalyst 40, are respectively called adiabatic temperature, a functionof the objective inlet temperature and objective intermediatetemperature (Tad_catinter), adiabatic temperature, a function of theobjective inlet temperature and objective outlet temperature(Tad_catout).

The electronic processing unit 30 calculates the Tad_catinter, using thecompressed air pressure at the outlet of the compressor 50, theobjective intermediate temperature of the catalyst, and the objectiveinlet temperature of the catalyst.

The electronic processing unit 30 then calculates the Tad_catout, usingthe compressed air pressure at the outlet of the compressor 50, theobjective inlet temperature of the catalyst 40 and the objective outlettemperature of the catalyst 40.

The Tad_catout and Tad_catinter are calculated by fixing for thecatalyst inlet temperature, the temperature in the intermediate catalystphase and catalyst outlet temperature, a pre-established value calledobjective.

The electronic unit 30 subsequently compares the Tad_catinter value withthe Tad_catout value, selecting the minimum value of the two.

This minimum value is the objective adiabatic temperature.

The electronic processing unit 30 then determines, on the basis of theobjective adiabatic temperature, the regulation of the second airdistribution valve 21 to reach the objective adiabatic temperature.

The position of the second air distribution valve 21 is evaluated by theelectronic processing unit 30 by calculating the flow-rate of the airsucked by the compressor 50.

The electronic data processing unit 30 calculates the air flow thatenters the combustion chamber 11 using the compressor 50 maps, memorizedin the data base.

These maps compare the air flow of the compressor 50 with themeasurement of the compression ratio of the compressor 50 at differentrates of the turbine measured, and at different positions of the statorblades at the mouth of the compressor 50.

As the fuel flow-rate is known, the control and regulation system thencalculates how much flow must be distributed to the second regulationvalve 21 in order to obtain the air flow-rate into the combustionchamber, necessary for reaching the adiabatic temperature defined above.

The functioning of the catalyst within the temperature range whichguarantees its correct functioning, is obtained through the regulationof the first fuel distribution valve 20 between the first combustionarea 12 and the second combustion area 13. The regulation system ensuresthat the inlet temperature of the catalyst 40 reaches such a value as toguarantee that the temperatures of the catalyst remain within the rangewhich assures its correct functioning.

The electronic unit 30 first calculates the adiabatic temperatureestimation on the basis of the measurement of the pressure andtemperature supplied by the compressor 50, on the basis of the pressureand temperature measurement at the outlet of the turbine 80, on thebasis of the fuel flow-rate and on the basis of the atmospherictemperature value.

On the basis of the adiabatic temperature thus calculated, themeasurement of the pressure supplied by the compressor 50 and thetemperature value at the intermediate phase of the catalyst 40 which isto be reached, the electronic unit 30 calculates the inlet temperatureof the catalyst which guarantees the desired temperature at theintermediate phase of the catalyst 40.

In the same way, in relation to the adiabatic temperature calculated,the pressure supplied by the compressor 50 and the desired outlettemperature of the catalyst, the electronic unit 30 calculates the inlettemperature of the catalyst 40 which guarantees the outlet temperatureof the catalyst 40 equal to that to be reached.

The control system compares the inlet temperatures of the catalyst 40calculated with the maximum tolerable value of the same catalyst 40, thecontrol system then selects the minimum of all temperatures.

Furthermore, the control system compares the temperature thus obtainedwith the minimum value which enables combustion in the first area 12 ofthe combustion chamber and then takes the higher of the two.

The inlet temperature of the catalyst 40 thus obtained is that whichmust be reached through the regulation of the fuel distribution valve sothat the temperatures of the catalyst remain within the range whichguarantees its correct functioning.

In this way, it is always possible to reduce the CO and NOx emissions ofthe combustion unit (10) to the minimum, with variations in theenvironmental conditions, by maintaining the inlet temperature of thecatalyst at a pre-established value and contemporaneously limiting theoutlet and intermediate temperature of the catalyst 40 so as to increaseits useful life.

It can thus be seen that a control and regulation system of a combustionunit according to the present invention achieves the objectivesspecified above.

Numerous modifications and variants can be applied to the control andregulation system of a combustion unit of the present invention thusconceived, all included within the same inventive concept.

1. A control and regulation system of a combustion unit (10) of the typecomprising a combustion chamber (11) and a catalyst (40), said controland regulation system comprising: an acquisition device of signalsproportional to functioning parameters characteristic of the functioningstate of the combustion unit (10), an electronic data processing unit(30) connected to the signal acquisition device from which it receivessignals, a control and regulation program associated with saidelectronic data processing unit (30), a first fuel distribution valve(20), a second air distribution valve (21), a data base associated withsaid electronic data processing unit (30), said electronic dataprocessing unit (30) receives signals from the signal acquisitiondevice, processes them and regulates the opening of the first valve (20)and second valve (21) to minimize the polluting emissions of CO and NOxof the combustion unit (10).
 2. The control and regulation system of acombustion unit (10) according to claim 1, characterized in that saidsignal acquisition device comprises at least one sensor capable ofdetecting at least one signal proportional to a functional parametercharacteristic of the functioning state of the combustion unit (10). 3.The control and regulation system of a combustion unit (10) according toclaims 1 and 2, characterized in that said signal acquisition devicecomprises a series of sensors suitable for detecting signalsproportional to parameters characteristic of the functioning state ofthe combustion unit (10).
 4. The control and regulation system of acombustion unit (10) according to claim 3, characterized in that saidseries of sensors comprises a set of temperature sensors.
 5. The controland regulation system of a combustion unit (10) according to claim 4,characterized in that said series of temperature sensors comprises afirst set of temperature sensors (60), a second set of temperaturesensors (61) and a third set of temperature sensors (62).
 6. The controland regulation system of a combustion unit (10) according to claim 3,characterized in that said series of sensors comprises pressure sensors(63) and pressure sensors (65).
 7. The control and regulation system ofa combustion unit (10) according to claim 4, characterized in that saidseries of temperature sensors comprises temperature sensors (64) andtemperature sensors (66).
 8. The control and regulation system of acombustion unit (10) according to any of the previous claims,characterized in that said combustion chamber (11) comprises a firstarea (12), a second area (13) in which the catalyst (40) is housed, athird area (14), a first fuel inlet duct (71), a second inlet duct (72)of the air coming from the compressor 50 and an outlet duct (73) of theexhaust gases.
 9. The control and regulation system of a combustion unit(10) according to claim 8, characterized in that said combustion chamber(11) comprises a third fuel inlet duct (74), an air distribution duct(75) and a main fuel duct (70).
 10. The control and regulation system ofa combustion unit (10) according to claim 9, characterized in that themain fuel duct (70) is connected to the first valve (20) which in turnis connected to the first fuel inlet duct (71) and to the third fuelinlet duct (74) to distribute the fuel in the first area (12) and secondarea (13) of the combustion chamber (11).
 11. The control and regulationsystem of a combustion unit (10) according to claims 5 and 8,characterized in that said first series of temperature sensors (60) ispositioned between the first area (12) and the second area (13) close tothe catalyst (40).
 12. The control and regulation system of a combustionunit (10) according to claims 5 and 8, characterized in that the secondseries of temperature sensors (61) is positioned close to the catalyst(40) between the second area (13) and the third area (14) of thecombustion chamber (11).
 13. The control and regulation system of acombustion unit (10) according to claims 5 and 8, characterized in thatthe third series of temperature sensors (62) is positioned in the thirdarea (14) of the combustion chamber (11).
 14. The control and regulationsystem of a combustion unit (10) according to claim 8, characterized inthat said combustion unit (10) is connected to a compressor (50) and aturbine (80) by means of the second compressed air inlet duct (72) andby means of the outlet duct (73), respectively.